Method of forming an electric heating unit



Aug. 11, 1925.

F. H. M QORMiCK METHOD OF FORMING AN ELECTRIC HEATING UNIT Filed July 6, 1923 IPA/enter": Fran cis H. Mo CormicK y His Attorney.

- Patented Aug. 11, 1925.

UNITED STATES 1,549,590 PATENT. OFFICE.

FRANCIS H. MCCORMICK, OF OAK PARK, ILLINOIS, ASSIGNOR TO EDISON ELECTRIC APPLIANCE COMPANY, INC. OF CHICAGO, ILLINOIS, A

YORK.

CORPORATION 0']? NEW ivrnrnon OF FORMING ANELECTRIC HEATING UNI-T.

Application filed July 6,

To all whom it may CO'ILCQIfl-Z Be it known that I, FRANCIS H. McCon- MIoK, a citizen of the United States, residing at Oak Park, county of Cook, State of Illinois, have invented certain new and useful Improvements in Methods of- Forming an Electric Heating Unit, of which the following is a specification.

My invention relates to electric resistance heating units and has for itsobject the provision of a simple, reliable and efiicient mechanical and electrical connection between a resistance conductor and a terminal or terminal lead.

In the construction oi resistance heating.

units for electric heaters it is customary to connect the terminal or terminal leads to the resistance conductor by means of silver soldered or brazed joints. It has been found to be very difficult, however, to make a uni' form silver soldered or brazed joint, and likewise difficult to determine whether the joint is satisfactory or not. Moreover, the high temperature to which the wire is sub jected during the brazing operation weakens it so that the resistance wire often breaks at. the joint.

In carrying out my invention I provide a metallic member having an aperture in which the resistance conductor and terminal lead are inserted and secured mechanically by compressing the member and then se cured electrically by electric welding.

For a more complete understanding of my invention reference should be had to the accompanying drawing in which Fig. 1 is a fragmentary plan view showing the parts assembled prior to the making of the joint; Fig. 2 is an elevation view partially in section of Fig. 1; Figs. 3 and 4c are plan and elevation views, respectively, similar to r joint; while Fig. 6 is a view looking upward of Fig. 5.

Referring to the drawing, I have shown my invention in one form as applied to the making of a joint between resistance conductors 10 and 10 made of a suitablematerial such as a nickel chromium alloy, and a terminal or terminal lead 11 made of a suitable material which may be pure nickel. The terminal lead 11 carries on its opposite 1923. Serial No. 649,779.

end a suitable terminal member 12. Although I have shown my invention as applied to the making of a joint between two sections 10 and 10 of a resistance heating unit as, for example, in. making an intermediate tap in the resistance heating unit, it is obviously applicable without change in procedure to the connection of a terminal lead to the extremities of an electric heating unit.

In one form of my invention I providev a soft iron member 13 which may be and pref erably is a common soft iron rivet. This member is provided with a longitudinal bore 14in which the ends of the resistance conductors 10 and 10 are inserted and also the free end of the terminal lead 11 as shown in Figs. 1 and 2; The head of the member 13 is provided with a lateral slot 15 intersecting the bore 14. Preferably the terminal lead is positioned central of the bore 1 L with the resistance conductors l0 and 10* on opposite sides and aligned with the slot 15. The resistance conductors 10 and 10 are bent laterally at the bore 14: so as to lie in the slot 15 and extend in opposite directions at right angles to the terminal lead 11-.

After the resistance conductors, the terminal lead, and member 13 have been assembled, as shown in Figs. 1 and 2, the head of themember 13 is staked or punched on each side' of the groove 15 so as to close the groove around the ends of the resistance conductors and secure them in place while the body portion 13 of the member 13 is compressed and flattened out somewhat so as to secure the terminal lead 11 and also further secure the resistance conductors, as shown in Figs. 3 and 4. This provides a good mechanical joint between the various parts but this mechanical joint does not assure a permanent electric connection between the terminal lead and the resistance conductors. In the next step, shown in Figs, 5 and 6, I provide a permanent electric connection by applying the jaws 16 and '17 of a suitable electric welding machine to opposite sides of the flattened body portion 13 of the member 13. A heavy electric current is then momentarily passed through the body portion 13, in a well known manner, for example, by means of a low voltage transformer 18 having its low voltage terminals connected to the jaws 16 and 17 In this l l v manner the soft iron. member 13 1S securely welded to the resistance conductors and the terminal lead whereby a permanent electrical connection is made.

5 This joint provides a reliable, and eflicient mechanical andelectrical connection between the terminal lead and the resistance conduc tors.

easily and quickly made, that uniform re sults are secured, and that the electric welding process does not raise thetemperature of the resistance conductor to a point where the quality of the material is afiected.

.The terminal member 12 also may be con- 15 nected to the end of the terminal lead by making first-a mechanical and then an electrical connection. The terminal is provided with a slot 19 and with a registering bore 20 into which the terminal lead is inserted,

2 0 as shown in Fig. 2.. Opposite sides of the terminal lead are then compressed or bent over against the terminal lead whereby the resistance lead is mechanically secured. An electrical connection is then made by apply- 'ing the jaws'of an electric welding machine to opposite sides of the terminal in thevicinity ofthe bore 20 at point 21 so as to make a welded'joint, and hence a permanent electrical connection.

\Vhile I have described my invention as embodied in concrete form and as operating in a specific manner in accordancewith the rovisions of the patent statutes, it should understood that I do not limit my invention thereto, since various modifications It has the advantages that it may be thereof will suggest themselves to those skilled in the art without departing from the spirit of in invention, the scope of which is set fort in the annexed claims.

What I claim as new and desire to secure by Letters Patent of the United States 1S: 1

1. The method of securing a terminal to a resistance conductor which consists in mechanically securing the ends of said'conductor and terminal to ether through the 3. The method of securing a terminal to a resistance conductor which consists in inserting said resistance conductor and ter minal in an aperture in a soft metallic member, compressing said metallic member to form a mechanical connection between the parts, and then electrically welding said member, resistance conductor and terminal to form a permanent electrical connection. In witness whereof I have hereunto set my hand this 2d day of July, 1923;

FRANCIS H. MCCORMICK. 

